I run on a fairly bumpy and dusty outdoor track in aus. Went from standard AE brown/green springs to Losi orange 22/yellow22. I figured these would be similar tension but actually the losi set were much firmer. Too firm for my track.
So I am now back to the AE springs with much more success.
I will try the losi red/white set next and see how they go.

The traxxas collars work but they make it hard to spin the threaded collar as they are not threaded them selves and they stop you from getting a decent grip on the threaded collars which they sit up against. pretty annoying actually. If you have the money, get the ghea collars.